1. Field of the Invention
This invention relates to oil compositions comprising crude oils, mineral oils, fuel oils and synthetic oils having one or more improved characteristics, such as pour point, viscosity, viscosity index, flowability and the like.
Crude, refined and synthetic oils frequently require modification or the addition of additives to improve one or more of their physical characteristics, such as, pour point, viscosity, viscosity index, etc. In particular, one more more of the abovedescribed properties is imparted to oil compositions by the addition thereto of terpolymers comprising (1) an alkyl ester of unsaturated monocarboxylic acid, (2) an olefinically unsaturated homo or heterocyclic-nitrogen compound and (3) allyl acrylate or methacrylate or a perfluoroalkyl ethyl acrylate or methacrylate. The copending application of Hanh T. Le, entitled "Terpolymers Of Alkyl Acrylates Or Methacrylates, An Unsaturated Homo Or Heterocyclic-Nitrogen Compound And Allyl Acrylate Or Methacrylate Or Perfluoroalkyl Ethyl Acrylates Or Methacrylates", Ser. No. 07/265,602, filed Oct. 31, 1988, describes in detail how to prepare these compounds.
Crude oils, depending upon the location of production may contain substantial quantities of wax. This wax is subject to separation when the crude oil is cooled below the pour point index of the oil. Crystallized wax precipitates from crude oil at sufficiently low temperatures and the oil, as well, can completely solidify causing reduced flowability and or pumpability of the oil.
When crude oil is produced from a production well through strata having lower temperatures than that of the oil-bearing formations, the crude oil may gel or transform into a dense or glutinous consistency, which can interfere with its transfer to the surface. The problem of crude oil and oil compositions solidifying, especially during extreme weather conditions is further emphasized during the storage of the oil in tanks which do not have insulation or heating facilities or in transporting the oil in unheated tankers or through a pipeline.
Thus, acceptable pour points and flow characteristics of an oil composition is highly desirable, particularly during production and upon storage, and transport of the oil composition; and especially during a refining operation when the oil composition is a crude oil. It should be noted that the terpolymers herein, when incorporated in an oil composition, substantially lower the pour point and concomitantly enhance the flowability of the oil composition.
2. Description of the Prior Art
Processes and catalysts for the production of polymers of alkyl acrylates and alkyl methacrylates and/or heterocyclic-nitrogen compounds and oil compositions containing the same are known and are currently practiced commercially.
For example, U.S. Pat. No. 2,889,282, issued June 2, 1959, relates to lubricating oil compositions containing an oil soluble copolymer consisting of (1) a monovinyl-substituted pyridine, and (2) a mixture of a C.sub.16 to C.sub.20 alkyl ester of an acrylic acid and a C.sub.10 to C.sub.14 alkyl ester of an acrylic acid. The polymers are described as possessing particularly good pour point depressing properties.
U.S. Pat. No. 3,260,728, issued July 12, 1966, discloses a process for polymerizing ethylene with lauryl methacrylate and n-vinyl-2-pyrrolidone at increased temperature and pressure, using benzene as a solvent and di-t-butyl peroxide as a promoter. The polymers are described as oil additives which impart improved flow of fuel at low temperatures and improved pour point characteristics to middle distillates.
U.S. Pat. No. 3,868,231, issued Feb. 25, 1975, relates to residual fuels having improved low temperature flow properties. The residual fuel flow property is enhanced by the addition thereto of a copolymer of a C.sub.18 to C.sub.28 alkyl ester of acrylic acid and 4-vinylpyridine.
U.S. Pat. No. 3,957,659, issued May 18, 1976, discloses a copolymer which imparts improved low-temperature flow properties to crude oils having a high wax content. The copolymers consist of a C.sub.14 to C.sub.30 alkyl ester of acrylic or methacrylic acid and 4-vinyl pyridine.
U.S. Pat. No. 4,161,392, issued July 17, 1979, relates to nitrogen containing copolymers which are suitable for use as carburetor detergents and corrosion inhibitors. The copolymers consist of the olefin polymerization product of (1) a C.sub.1 to C.sub.4 alkyl methacrylate or aromatic ester of an unsaturated aliphatic mono-, di- or polycarboxylic acid, (2) a C.sub.8 to C.sub.20 saturated or unsaturated, substituted or unsubstituted, aliphatic or aromatic ester of an unsaturated mono-, di- or polyaliphatic carboxylic acid having 1 to 6 carbon atoms, and (3) an ethylenically unsaturated compound containing a nitrogen atom, e.g., dimethyl amino ethyl methacrylate acid or 4-vinyl pyridine.
It must be noted, however, that oil compositions containing the specific terpolymers comprising the alkyl esters of unsaturated monocarboxylic acid, olefinically unsaturated homo or heterocyclic-nitrogen compounds, and allyl acrylate or methacrylate or perfluoroalkyl ethyl acrylates or methacrylates claimed herein are new.